S385
Clinical - CNS
ESTRO 2026
were received, of which 111 were approved on first submission. Breakdown by case is detailed in Table 1. GTVs were well contoured (average pass rate of 89%). OAR resubmissions were common, with brainstem and pituitary showing the poorest agreement. DICE scores highlight contouring variations; however, DICE is highly susceptible to structure size and low scores did not always translate to unacceptable contours. Although many submissions observed acceptable variations, there was a lack of consensus in some aspects of clinical practice (Table 2).
and visual improvement. Keywords: Pituitary adenoma, proton radiotherapy
Digital Poster Highlight 3865 Is there consensus in contouring for SRS indications? Results from a national radiotherapy quality assurance program Patricia Diez 1 , Neil Kitchen 2 , Catherine McBain 3 , Luke Gilling 1 , Rushil Patel 1 , Paul Sanghera 4 1 National RTQA, Radiotherapy Trials Quality Assurance Group, Mount Vernon Cancer Centre, London, United Kingdom. 2 Victor Horsley Department of Neurosurgery, National Hospital for Neurology and Neurosurgery, UCLH NHS Trust, London, United Kingdom. 3 Clinical Oncology, The Christie NHS Foundation Trust, Manchester, United Kingdom. 4 Department of Oncology, University Hospitals Birmingham NHS Foundation Trust, Birmingham, United Kingdom Purpose/Objective: A radiotherapy QA program was implemented as part of a national plan for the accreditation and re- accreditation of SRS services for new and existing providers, respectively. The aim was to ensure consistent, high-quality SRS was delivered across all centres. Commissioned intra-cranial conditions were stratified by indication: metastases, meningiomas, vestibular schwannomas and pituitary adenomas to be treated at all commissioned providers; arteriovenous malformations, trigeminal neuralgia and paediatric CNS tumours to be treated at specialist centres. As part of the radiotherapy QA program, delineation of target volumes and OARs was assessed. Results for indications treated at all sites are reported here and differences in approach evaluated. Material/Methods: Contouring benchmark cases for multiple metastases, cavernous sinus meningioma, vestibular schwannoma and pituitary adenoma were circulated to 20 centres. These included a planning CT and MR-imaging. Two clinicians from each centre were invited to contour GTV and PTV for each indication. All intra-cranial OARs were assessed for the metastases case only, following published guidelines [1]. All submissions were reviewed against agreed consensus volumes by at least 1 clinician (neuro-surgeon or neuro-oncologist) and 1 medical physicist from the review team. Unacceptable contours were asked to be resubmitted. Contouring variations were analysed to identify differences in contouring approach. Results: A total of 157 submissions across 4 benchmark cases
Conclusion: Variations in practice were observed across all clinical indications reviewed. Use and interpretation of imaging will impact practice: Gamma Knife centres have MR-only workflows, with the rest planning on CT- MR fusion. Often, contours outlined on MR were not adjusted to CT anatomy. Some differences may also be due to auto-contouring software discrepancies, however information of its use within the program was not collected. The results from this program have highlighted the need for national guidelines for SRS including more detail on use of imaging, target localisation and a contouring atlas to help standardise practice. Participation in peer review and radiologist input are also key to consistent and accurate
contouring. References:
1. Mir R, Kelly SM, Xiao Y, Moore A, Clark CH, Clementel E, et al. Organ at risk delineation for radiation therapy
Made with FlippingBook - Share PDF online